As a rule, because of their inadequate bonding to rubber, textile reinforcement substrates of polyester, polyamide or aramide (e.g. Kevlar.TM.) fibers require pre-treatment with adhesion promoters, the latter of which are applied either when the fibers are manufactured or when the textile is prepared. Especially suitable adhesion promoters are epoxides and isocyanates, as well as blocked isocyanates; isocyanates with a polyfunctional structure are especially preferred. Other suitable adhesion promoters are disclosed in EP-A-0 459287 (corresponding to U.S. Pat. No. 5,229,202) and EP-B-0 194 678 (corresponding to U.S. Pat. No. 5,032,454).
In order to enhance the effectiveness of such adhesion promoters and especially to improve their penetration into the fiber or textile reinforcement substrate, such adhesion promoters are generally used in the form of solutions of organic solvents. However, such organic solvents are hazardous to health and require major efforts and expenditures to prevent air pollution and for recovery and reprocessing. The need therefore exists for solvent-free adhesion promoter systems.